1. Technical Field
The present invention relates to a magneto generator for generating an electric power utilizing electromagnetic induction between magnets and armature winding by rotating a flywheel.
2. Background Art
FIGS. 11 and 12 show a rotor of a conventional flywheel-type magneto generator disclosed in the Japanese Utility Model Publication (unexamined) No. 121380/1992. FIG. 11 is a sectional view taken along the line XIxe2x80x94XI of FIG. 12, and FIG. 12 is a sectional view taken along the line XIIxe2x80x94XII of FIG. 11. Reference numeral 1 is a bowl-shaped flywheel formed by a circumferential wall portion and a side wall portion on one end side of the circumferential wall portion. Numeral 2 is a magnet, and plural magnets 2 are arranged in the circumferential direction on the circumferential wall portion of the flywheel 1 so as to be engaged with projections 1a arranged on the inside of the circumferential wall portion. Numeral 3 is a cylindrical guard ring formed by drawing a metal plate and having flange portions 3a formed at one end by bending, and this guard ring 3 is in close contact with the inside the magnets 2 arranged annularly. Numeral 4 is a resin with which both side portions of the magnets 2 and spaces between end portions of the respective magnets 2 are filled to fix the magnets 2 and the guard ring 3 integrally onto the flywheel 1. Numeral 5 is a boss portion mounted on a rotary shaft (not shown in the drawings) fixed to the center of the side wall portion of the flywheel 1. Numeral 4a is fins 4a arranged on the inside wall portion of the flywheel. Another end side of the circumferential wall portion of the flywheel 1 is an opening side freely open. Numeral 1b shows step portions 1b formed by extrusion molding on the inside of the circumferential wall portion at several places in the whole circumference of the flywheel 1.
Next, operation of the conventional rotator is hereinafter described. The boss portion 5 mounted on the rotary shaft (not shown) and the flywheel 1 are rotated by rotation of the rotary shaft. Accordingly, the fins 4a arranged on the inside wall portion of the flywheel 1 stir air between a magneto coil and the side wall of the flywheel 1 and cool the magneto coil.
In the rotor of the above conventional magneto generator, it is certain that air in the flywheel is stirred, but ventilation inside the flywheel is not sufficient. On the other hand, the armature winding serving as the magneto coil generates a heat in proportion to square of the generated current. As described above, since ventilation is insufficient, it is difficult to change the heated air, and this causes a problem that rise in resistance value due to temperature rise of the winding cannot be sufficiently controlled and the generated current is lowered.
The present invention was made to resolve the above-discussed problems and has an object of obtaining a magneto generator in which ventilation inside a flywheel is efficiently performed to prevent temperature rise of an armature winding serving as a magneto coil, and a generated current is prevented from lowering.
A magneto generator according to the invention comprises: a bowl-shaped flywheel formed by a circumferential wall portion and a side wall portion on one end side of the circumferential wall portion; plural magnets arranged on an inner peripheral surface of the mentioned flywheel; and a magneto coil which is arranged in the mentioned flywheel so as to oppose to the mentioned magnets and generates an electric power utilizing electromagnetic induction between the mentioned magneto coil and the mentioned magnets; in which the mentioned flywheel has plural vent holes on the side wall portion and is provided with fins arranged between neighboring two vent holes and protruding toward the inside of the flywheel so that outside air may be introduced in the flywheel or inside air may be discharged therefrom during rotation of the flywheel.
As a result, during rotation of the flywheel, air is effectively introduced from outside of the flywheel through the vent holes or air in the flywheel is effectively discharged to outside through the vent holes, whereby it is possible to improve power generation efficiency.
Another magneto generator according to the invention comprises: a bowl-shaped flywheel formed by a circumferential wall portion and a side wall portion on one end side of the circumferential wall portion; plural magnets arranged on an inner peripheral surface of the mentioned flywheel; and a magneto coil which is arranged in the mentioned flywheel so as to oppose to the mentioned magnets and generates an electric power utilizing electromagnetic induction between the mentioned magneto coil and the mentioned magnets; in which the flywheel has plural vent holes on the side wall portion and fins are formed so as to surround circumference and inside of the vent holes so that outside air may be introduced in the flywheel or inside air may be discharged therefrom through holes formed on the fins.
As a result, during rotation of the flywheel, air is effectively introduced from outside of the flywheel through the vent holes or air in the flywheel is effectively discharged to the outside through the vent holes, whereby it is possible to improve power generation efficiency.
In the magneto generator according to the invention, it is preferable that the fins are formed integrally by a resin, the mentioned resin filling a space between a cylindrical guard ring arranged on the inside of the magnets and the flywheel, and the magnets are embedded in the resin.
As a result, any separate process is not necessary to form the fins, and it is possible to manufacture the magneto generator at a reasonable cost.
In the magneto generator according to the invention, it is preferable that the holes formed on the fins surrounding the inside of the vent holes are open so that center axis of each hole may be inclined with respect to the rotational direction of the flywheel.
In the magneto generator according to the invention, it is preferable that the holes formed on the fins surrounding the inside of the vent holes are open so that backside portions in the rotational direction of the flywheel may be inclined with respect to the rotational direction.
In the magneto generator according to the invention, it is preferable that the fins surrounding the circumferences of the vent holes are arranged so that backside portion of the flywheel in the rotational direction may protrude toward inside or outside of the flywheel.
As a result, it is possible to introduce the outside air and discharge the heated air in the flywheel to outside more effectively.